Studies showed that stimulant drugs that affect the monoaminergic system alter both behavioral and cognitive processes. The aim of the present study was to investigate the impact of prenatal and acute methamphetamine (MA) exposure on cognitive functions of adult male rats tested in Morris water maze (MWM). We tested adult male rats prenatally exposed to MA (5 mg/kg), saline or no injection. Half of the animals were injected daily with MA (1 mg/kg) after finishing the testing. All injections were administered subcutaneously. Three types of tests were used: (1) "Place navigation test" (Learning), (2) "Probe test" (Probe) and (3) "Retention memory test" (Memory). Our results showed that prenatal MA exposure did not affect the test of learning and the Probe test. In the test of memory prenatally MA-exposed rats had lower latencies than animals prenatally exposed to saline. Further, acute MA administration increased the speed of swimming in all rats regardless of prenatal drug exposure and the type of test and, however, the increase in the speed was significantly greater in rats prenatally exposed to MA than in rats without any prenatal exposure. In addition, acute MA application significantly prolonged trajectories in the Place navigation test. The present study thus demonstrates that: (1) Prenatal MA exposure does not affect learning in the MWM. (2) Prenatal MA exposure increases the sensitivity to acute drug injection. (3) Acute MA application impairs learning in the MWM.

Charles University Prague 3rd Faculty of Medicine Department of Normal Pathological and Clinical Physiology Prague Czech Republic

The Impact of Neonatal Methamphetamine on Spatial Learning and Memory in Adult Female Rats

Prenatal Exposure to Methamphetamine: Up-Regulation of Brain Receptor Genes